I first saw the gassifier on Mountain Men TV show. This guy shows you how to build a simple one to run a generator. Great watch for those that want to try to be self-sufficient. Building a No-Weld Woodgas

In entrained bed gasifiers, fine coal feed and the oxidant (air or oxygen) and/or steam are fed co-currently to the gasifier. Gasification is the conversion by partial oxidation at elevated temperature

Best stove I ever made. Extracting gas from twigs and lighting it. I was using it every day, while walking with my backpack. Total cost of making - 2 euro.